Compound battery device having lithium battery and lead-acid battery

Abstract

A compound battery device having a lithium battery and a lead-acid battery includes at least one lithium battery unit, at least one lead-acid battery unit and a control circuit. The lithium and lead-acid battery units are electrically connected in parallel and can have various combinations to meet actual demands of an output voltage. The control circuit is electrically connected to the lithium and lead-acid battery units separately and further comprises a voltage-boosting unit, a voltage-detecting unit, a lithium battery unit management unit and a logic control unit. Thereby, two complementary battery units are connected in parallel, with a control circuit to adjust a voltage thereof, allowing the two battery units to work together to make use of their respective advantages while providing mutual power support. Thus, the compound battery device is capable of more efficient power supply and higher loading, and effectively prevents over-discharge that shortens the battery service life.

1 . A compound battery device having a lithium battery and a lead-acid battery, comprising:
 at least one lithium battery unit;   at least one lead-acid battery unit; and   a control circuit,   wherein the lithium battery unit and the lead-acid battery unit are electrically connected in parallel and can have various combinations to meet actual demands of an output voltage; and the control circuit is electrically connected to the lithium battery unit and the lead-acid battery unit separately and further comprises a voltage-boosting unit, a voltage-detecting unit, a lithium battery unit management unit and a logic control unit.   
     
     
         2 . The compound battery device as claimed in  claim 1 , wherein a voltage of the lead-acid battery unit is automatically detected as a reference point, so that a voltage of the lithium battery unit is raised accordingly by the voltage-boosting unit to be equal to the voltage of the lead-acid battery unit. 
     
     
         3 . The compound battery device as claimed in  claim 2 , wherein the voltage-boosting unit has a voltage-boosting range from 0 to 13%. 
     
     
         4 . The compound battery device as claimed in  claim 1 , wherein the lithium battery unit is one of a lithium-ion battery and a lithium-polymer battery. 
     
     
         5 . The compound battery device as claimed in  claim 1 , wherein one of the various combinations of the lithium battery unit and the lead-acid battery unit comprises five series-connected lead-acid batteries having a total voltage of 60 V and fourteen series-connected lithium batteries having a nominal voltage of 53.2 V. 
     
     
         6 . The compound battery device as claimed in  claim 1 , wherein one of the various combinations of the lithium battery unit and the lead-acid battery unit comprises four series-connected lead-acid batteries having a total voltage of 48 V and twelve series-connected lithium batteries having a nominal voltage of 45.6 V. 
     
     
         7 . The compound battery device as claimed in  claim 1 , wherein one of the various combinations of the lithium battery unit and the lead-acid battery unit comprises three series-connected lead-acid batteries having a total voltage of 36 V and eight series-connected lithium batteries having a nominal voltage of 30.4 V. 
     
     
         8 . The compound battery device as claimed in  claim 1 , wherein one of the various combinations of the lithium battery unit and the lead-acid battery unit comprises two series-connected lead-acid batteries having a total voltage of 24 V and five series-connected lithium batteries having a nominal voltage of 19 V.